1. Field of the Invention
The invention concerns a process for laying underground collector mains for liquids and gases, in particular for the construction of horizontal filter wells and drainage mains, as well as a tool for carrying out the process.
2. Description of the Related Art
The construction of horizontal, arcuate, inclined or helical wells and drainage mains both for ground water and catchment water as well as for ground air, is summarily provided with the designation horizontal filter well construction. Conventional horizontal filter wells are used for the removal of ground water, which is led through horizontally disposed filter pipes into a vertical main shaft. From there, the water is brought to the surface by means of pumps. In the fields of old waste sanitation and security this type of wells can be used for the removal of noxious substances. Such horizontal filter wells have economic advantages of a technical process nature when compared with vertical wells and under certain circumstances.
With a horizontal filter well, the ground layer which conducts the ground water with a greater well capacity, corresponding to its yield, can be included. Furthermore, horizontal filter wells become ocherous significantly more slowly than vertical wells, because the horizontally positioned filter pipes do not come into contact with the air and the flow speeds in horizontal water inlets can be kept very low.
As a further advantage, it should be emphasized that the mechanical and pipe technology installations for pump pressure mains, measuring instruments and power supplies with electrical switching and control units demand a far smaller volume than in the case of vertical wells. Equally, the supervision and maintenance of a horizontal filter well, when measured against comparable vertical well installation, are not so costly.
In addition to the extraction of water, horizontal filter wells are in principle preferred for use where relatively level water reserves have to be sanitized, or in strongly layered ground, where a particular layer has to be opened up for the sanitation of the ground air. Moreover in areas which are built up or where a different type of use does not permit the construction of vertical layers, or where there are hydraulic needs, which make obvious the construction of a horizontal filter well, horizontal filter wells are used for preference.
Today, for horizontal filter wells primarily the processes in accordance with FEHLMANN and PREUSSAG are used. The processes in accordance with FEHLMANN and PREUSSSSAG are described in E. Bieske, "Bohrbrunnen" (7th edition, 1992, Oldenbourg, Munich). In addition, the Preussag firm issues a brochure in which the Preussag process is described in detail. The modus operandi will be briefly explained using the example of the Preussag process: in this process, a main shaft which reaches as far as the ground water reserve is previously prepared and plugged. From one working plane, radiating or fan-shaped straight horizontal bores are constructed with bore pipes. In these bore pipes, the filter pipes are then installed. Then the bore pipes are gradually extracted from the bores, while filter gravel is washed into the cavity between the bore and the filter pipe under high pressure, so that the filter gravel can be deposited between the wall of the bore and the filter pipe. This filter jacket can consist of filter gravel or of filter sand. These known processes have the disadvantage that a vertical shaft having a width of at least 2.5 m in diameter has to be constructed in the soil. Furthermore, a work platform has then to be built with the bore and insertion installation in the shaft, and the horizontal bores have to be produced in the soil layers at great cost.
The horizontal bores in this process can only achieve a limited length of up to about 60 m, and this only when they are straight. The possible lengths of the bore are predetermined by the soil properties.
In addition, during the entire construction period of the horizontal filter well, when using the known processes, ground water flows constantly into the central shaft, which has either to be prevented or has to be pumped at great cost.
These known processes are therefore laborious, costly and can only be built economically as from predetermined magnitudes.
It is the object of the present invention to develop a totally new process, which makes the simple introduction, which can be rapidly carried out, of underground horizontal filter wells and drainage mains possible, as well as to provide a tool for the implementation of the process.